I've centered the nav bar before on other sites, and although I've made those suggested changes to the #access and #access ul, there is still something off that is making my nav bar align left (or so it seems to me).

which I added to my child theme's style.css only to find that it completely disregarded all the color/style edits I have created thus far (made the bar black with white text, as it is in the original twenty eleven)
.